1. Field of the Invention
This invention is directed to a telescoping gripping and lift assembly designed for lifting and securing large hay bales and other large objects, such as rectangular trash containers, onto an elevated flat surface, such as the bed of a flat bed truck. More particularly, the gripping and lift assembly includes an opposed pair of gripper arms which are each selectively movable between raised and lowered positions, grip and release positions, and telescopically extended and retracted positions.
2. Description of the Related Art
In the past, hay for feeding livestock was cut and baled into relatively small, rectangularly shaped hay bales weighing about 100 pounds. These bales could be readily lifted and handled by a man acting alone and required storage out of the weather in barns or other storage buildings. When the hay was needed for feeding cattle, a desired number of these small hay bales were simply removed from storage, brought to the livestock and broken open for feeding.
For economic reasons, including reducing labor costs and storage requirements, this method of storing hay in small bales has been largely replaced by the use of large hay bales weighing upwards of 2000 lbs. each. These large bales, which can be round or square, can simply be left in the field or stacked outdoors and removed only as they are needed for feeding. Thus, large bales do achieve the goals of reduced labor and storage costs.
However, such large bales do present handling problems. Their large bulk and weight make it physically impossible to move them manually. Therefore, farmers and cattle ranchers have needed specialized mechanical equipment for moving these large bales.
In addition, a need exists for loading and transporting free standing rectangular trash containers such as are commonly used by institutions such as schools, churches, etc.
A number of previous attempts have been made to create machinery which can be attached to a pick-up or flat bed truck to allow the lifting and transport of large hay bales.
U.S. Pat. No. 4,325,666 to Chain et al. is directed to a bale handling apparatus for a pick-up truck which is capable of loading and transporting two bales at once. This bale handler is necessarily large and complex and, once installed, essentially limits the pick-up to bale hauling tasks.
U.S. Pat. No. 4,564,325 (the '325 patent) to Ackerman is directed to a round bale loader for a flat bed truck which is designed to allow the truck to be also used for other, general purpose hauling and towing tasks. A pairs of bale gripper arms are connected to a frame which is pivotally attached to the rear of the truck. A hydraulic actuator is attached beneath the truck bed and is actuated to pivot the arms up and onto the bed. The arms can be drawn toward each other by a pair of hydraulic cylinders. When not in use, the arms are received and stored in grooves in the truck bed.
U.S. Pat. No. 4,594,041 (the '041 patent) to Hostetler is drawn to another round bale handling apparatus which employs a pair of gripper arms which can be urged together to grip a round bale and then pivoted up over the truck bed to transport the bale. A hydraulic actuator mounted beneath the vehicle bed is used to selectively pivot the arms along with a gripped hay bale up and onto the truck bed.
Both the '325 and the '041 patent are intended for use with a flat bed truck and are both designed to allow the truck to be used for other purposes when not loading or transporting hay bales. However, in both the '325 and the '041 patents, a bale gripping mechanism is operated via a transverse "squeeze" arrangement wherein a pair of hydraulic piston & cylinder units are selectively operated, pulling, in the '041 patent and pushing, in the '325 patent, a respective pair of fixed length arms transversely inward to engage a large bale. In the '041 patent, the arms are attached to respective telescoping square tubes which retract within a stationary square tube attached to the rear of the truck bed. In the '325 patent, a pair of elongate arms are pivotable toward each other to grip a bale positioned there between. A problem with both of these prior art arrangements is the limited reach of the gripper arms. In both the '325 and '041 patent, the lift operation is essentially limited to lifting a large bale off of the is ground and depositing it onto the flat bed, and vice versa. Thus, they do not allow a large bale to be lifted off of the flat bed and then raised to a position where it can be put into an bale feeder or the like.
In addition, hydraulic systems for the gripper arms on prior art systems such as the '041 patent typically use a "least resistant" hydraulic system in which hydraulic fluid under pressure is simultaneously supplied to independent gripping piston & cylinder units operating each respective gripper arms with the fluid entering the "least resistant" gripping piston & cylinder unit. This often causes an intermittent operation of the gripper arms as their gripping piston & cylinder units alternate being the least resistant. Also, since the view of an operator in the truck bed is often obscured by the bale being lifted, intermittent operation of the gripper arms prevents the operator from assuming that the position of a visible one of the arms is mirror image of the other.
It is clear then, that a need exists for a telescoping gripping and lift assembly capable of lifting large hay bales onto an elevated flat surface, such as a truck flat bed and for lifting the bales off of the flat bed and telescopically extending to allow deposit of the bale onto a feeder or other remote receptacle. The telescoping mechanism must remain rigid enough to support the bale in an extended position. Such a gripping and lift assembly should also be versatile enough to be used to lift and transport other large objects, such as rectangular trash receptacles. Finally, the gripping and lift assembly should preferably use a synchronized hydraulic gripping system which allows a bale or other large object to be uniformly gripped and secured with a smooth and continuous operation of the gripper arms and which allows an operator to view one gripper arm and determine that the opposite arm is in an equivalent position.